Well, Simon wasn't expecting that. After all, he was the one codenamed Phantom. He popped back into the ceiling and cautiously emerged from the hallway wall a few feet away. He stepped onto the floor and completely out of the wall, becoming solid as he quietly moved towards where he had last seen the strange looking man. He was trying to recall more about him, in case he had at some point heard about his power set and simply could not remember. Little did he know he had already been out-stealthed, for lack of a better term.
Simon walked close to the wall, looking over his shoulder and up and down the hall, counting the doors and possibilities as to where the man might have disappeared to in the space of time it took him to walk to the end of the hall and turn left. There weren't very many options.